title: A systematic review of air pollution and incidence of out-of-hospital cardiac arrest.
abstract: BACKGROUND
  Studies have linked air pollution with the incidence of acute coronary artery events and cardiovascular mortality but the association with out-of-hospital cardiac arrest (OHCA) is less clear.
  
  
  OBJECTIVE
  To examine the association of air pollution with the occurrence of OHCA.
  
  
  METHODS
  Electronic bibliographic databases (until February 2013) were searched. Search terms included common air pollutants and OHCA. Studies of patients with implantable cardioverter defibrillators and OHCA not attended by paramedics were excluded. Two independent reviewers (THKT and TAW) identified potential studies. Methodological quality was assessed by the Newcastle-Ottawa Scale.
  
  
  RESULTS
  Of 849 studies, 8 met the selection criteria. Significant associations between particulate matter (PM) exposure (especially PM(2.5)) and OHCA were found in 5 studies. An increase of OHCA risk ranged from 2.4% to 7% per interquartile increase in average PM exposure on the same day and up to 4 days prior to the event. A large study found ozone increased the risk of OHCA within 3 h prior to the event. The strongest risk OR of 3.8-4.6% per 20 parts per billion ozone increase of the average level was within 2 h prior to the event. Similarly, another study found an increased risk of 18% within 2 days prior to the event.
  
  
  CONCLUSIONS
  Larger studies have suggested an increased risk of OHCA with air pollution exposure from PM(2.5) and ozone.
authors.affiliation: Discipline of Emergency Medicine, The University of Western Australia, , Crawley, Western Australia, Australia.
authors.forename: Tiew-Hwa Katherine
authors.initials: TH
authors.lastname: Teng
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Williams
authors.forename: Alexandra
authors.initials: A
authors.lastname: Bremner
authors.forename: Hideo
authors.initials: H
authors.lastname: Tohira
authors.forename: Peter
authors.initials: P
authors.lastname: Franklin
authors.forename: Andrew
authors.initials: A
authors.lastname: Tonkin
authors.forename: Ian
authors.initials: I
authors.lastname: Jacobs
authors.forename: Judith
authors.initials: J
authors.lastname: Finn
mesh_terms: D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis / Q000706:statistics & numerical data; D016206:Databases, Bibliographic; D006801:Humans; D015994:Incidence; D058687:Out-of-Hospital Cardiac Arrest / Q000453:epidemiology / Q000209:etiology*; D010126:Ozone / Q000009:adverse effects* / Q000032:analysis; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis
chemical_list: D052638:Particulate Matter; D010126:Ozone
keywords: Air Pollution; Heart Disease; Mortality